Wireless devices such as laptop computers, palm-sized computing devices, two-way pagers, cellular phones and personal digital assistant (PDA) devices have become increasingly popular. Some of these devices enable the user to communicate with others vocally and through electronic mail and instant messaging, as well as to collect, analyze and distribute important information as the user travels. An important trend involves making the devices as small and compact as possible. While these advantages have been warmly embraced by the public, one disadvantage of the compactness, usefulness, easy accessibility and ubiquity of these devices is that the devices have now become increasingly vulnerable to theft or other unauthorized use.
Many computers, especially portable computers have been secured from unauthorized use through different preventive techniques. One previous method of preventing unauthorized use is an automatic logging off system. This system automatically logs off the computer if the computer device has been inactive for a specified period of time much like a computer screensaver. If an authorized user has logged onto a secure computer, but not entered any input for a predetermined period of time, the concern is that the authorized user might have discontinued use and left the computer unattended without securing the computer. Under these circumstances, if an unauthorized user can get to the computer during this time while the computer is still logged on, the unauthorized person will have full access to the information and resources on the computer. The likelihood of this occurring can be diminished by having the computer automatically log off if the computer goes unused for a specified period of time. With this approach, in order to obtain access again, the authorized user must log back onto the system by entering his or her password.
While the automatic timed lock approach is useful because it protects information and resources, it may also be an inconvenience to authorized users. In this regard, the authorized user is inconvenienced, and productivity is impaired, when the user has to log back in to the computer each time he or she has to leave the computer for a short period of time. Logging back on can become an annoyance if the process needs to be repeated in a nearly continuous manner in situations where the user is frequently away from the computer. A longer period of time for automatic log off can be provided but this undermines the effectiveness of the whole auto log off approach
Another preventative measure taken to secure information on computers is the use of a magnetic swipe card to unlock a computer once the computer has timed out. The computer time out mechanism works the same as the method described above, i.e., log off is automatic if the computer is not used for a specified period of time but instead of entering a password to regain access, a card is swiped through a reader which is associated with the computer. For example, such a reader may be attached to the computer by a daisy chain. This swiping of the card unlocks the computer.
Although the use of such a swipe card allows the user to unlock the computer without having to enter a password, the repetitive action of having to swipe the card through the reader each time the computer locks as a result of the user stepping away from his desk can still become annoying. Further, with the new generation of compact, mobile computer devices, the card reader itself may also be larger than the device being protected, thus defeating the convenience of having a mobile device. Also, the card may be left at the desk unintentionally, as swipe cards often are, thereby defeating the security provided by use of such a card.
A further type of security system that is of particular interest here is wireless locking systems that use a wireless signaling device to cause locking of another wireless-enabled device. For example, such systems are used to remotely control door locks for automotive vehicles, and in a number of other applications.
Patent publications of interest here include U.S. Patent Application Publication No. 2004/0178907A1 which relates to an alarm system for preventing loss or theft of a portable and/or movable device such as a mobile telephone. The system determines the distance between the telephone and another movable and/or portable device using the Global Positioning System (GPS) and an alarm is generated when that distance exceeds a predetermined distance. At least one of the devices may be locked when the alarm is triggered. Other patent publications of background interest include Publication Nos. U.S. 2004/0215816A1 and U.S. 2003/0184431A1.
U.S. Pat. No. 5,635,857 discloses a mobile phone alarm system including a phone device attached to the mobile phone and body device adapted to be carried by a user. The phone device repeatedly transmits a verification signal of limited power to the body device. The signal is only identifiable within a predetermined limited distance and if the separation distance between the devices exceeds this predetermined distance, the body device receives no signal and alarms.